Fluid pump



y 1969 WJJV. CALDWELL 3,444,817

FLUID PUMP Filed Aug. 23. 1967 Sheet of 2 INVENTOR WILLIAM J. CALDWELL 865mm. @MLJ ATTORNEYS May 20, 1969 w. J. CALDWELL FLUID PUMP Sheet L of 2 Filed Aug. 23, 1967 INVENTOR 3716-3 WILLIAM J. CALDWELL ATTORNEYS United States Patent U.S. Cl. 103-88 1 Claim ABSTRACT OF THE DISCLOSURE The invention relates to a fluid pump having an axial intake and an axial discharge and having a series of continuous vanes which may be of complex surface configuration, the leading end of each vane having an angular portion providing an axial impeller flow zone which merges downstream into a radially expanding, axially extending screw surface defining an axial screw flow zone, terminating in a trailing end having straight, forward or backward (rotationwise) curvature for determining the fluid delivery pattern, there being a centrifugal flow zone imposed upon the screw flow zone. The working surface of each vane is mounted on and has unitary movement with two rotating members mounted for rotation about a common axis, the radially opposed surfaces of the members having sealing relation with the longtudinal edges of each vane.

Background 0 the invention Devices for the acceleration of fluids of conventional design, for the most part, fall into two general classes when positive displacement pumps are excluded. One class involves pumps having axial intake and axial discharge and are known as impellers or screws. The other class has axial intake and radial discharge and they are known s centrifugal pumps and blowers. A hybrid design involving these two classes is known as a mixed flow impeller. Blowers in which there is a radial intake as well as a radial discharge are also known.

According to the invention the vanes of my improved fluid pump each represent a continuous working surface of changing configuration which functions first as an impeller having an axial intake, then as an expanding screw having centrifugal characteristics imposed thereon and a generally axial discharge of annular or doughnut shape.

Summary of invention Fluid pumps according to the invention have application to compressible as well as noncompressible fluids.

In its preferred form, the fluid pump of the invention comprises an inner or center dome-like member and an outer conical-like housing having a flared inlet and the housing revolves as a unitary part of the inner dome-like member, said inner member being hereinafter, for convenience of description, referred to as the center dome. Spacing the center dome and the outer housing are a plurality of vanes of complex shape which collectively define, between the inlet and the discharge ends of the fluid pump, an impeller section directly adjacent the flared inlet end of the outer housing and a screw section extending from the impeller section to the discharge end and the screw section providing centrifugal displacement of 'the fluid being propelled along the axis of rotation between the center dome and the outer housing.

At the inlet section of the fluid pump, according to the invention, the outer housing is preferably flared when air or other readily compressible fluid is being handled. In this area, the leading end of the vanes are of air scoop cross section and the flared inlet construction proice vides a restricted throat portion which provides precompression of the inlet fluid stream. Such a construction has been found, in practice, to reduce noise by equalizing pressures at the leading ends of the vanes as well as producing additional reactive axial thrust and greater fluid flow. Within the air scoop section of the pump the vanes are preferably bent in the direction of rotation so as to reduce the shock angle of initial acceleration of static and low velocity conditions.

More specifically, the fluid pump of the present invent comprises an outer conical-like housing with an inner dome-like member carrying the hub and shaft mount, the housing and member being spaced and supported from each other by vanes of complex shape to provide three major states of acceleration of the material being handled by the fluid pump, namely, an impeller stage, a centrifugal stage, and a screw stage, the centrifugal stage being superimposed upon the screw stage.

The blades of the fluid pump are preferably continuously attached along their longitudinal edges to the inner and outer surfaces of the outer and inner housing and member to avoid leakage between the vanes and the structure embracing their longitudinal edges which define the shape of the fluid stream flowing between the inlet and discharge ends of the fluid pump concentric with the axis of rotation.

A plurality of circumferentially positioned vanes of the fluid pump preferably each having a continuous working surfaces which embraces the three distinct integrated propelling stages of the pump. The initial air scoop stage of each vane is so shaped as to cut or slice into the particular fluid being handled to force the same into the expanding screw which embraces the compound capability of centrifugal force plus the screw action. Thus, the entrained fluid material is smoothly projected toward the annular or doughnut shaped rotating discharge opening of the fluid pump. In practice, to assure both maximum eficiency and capacity for handling the compressible fluids, it has been found that the area of the substantially round intake of the fluid pump should be in the order of 1.5 times the area of the annular or doughnut shaped discharge. This ratio also applies in the handling of noncompressible fluids for free discharge such as water aeration in sanitary lagoon operations where a large centrifugally coned water pattern is desired. This acceleration ratio leverage is considered a major factor in obtaining the smooth uniform transfer of energy from the propelling surfaces of the vanes of the fluid pump to the material being handled and, in practice, results in an operating efliciency in the order of over a relatively wide range of discharge pressures. In the handling of liquids and slurries against substantial head pressures, the comparative areas of the inlet and discharge ends of the fluid pump should be substantially 1 to 1 for good efl'iciency.

By imparting a forward curvature to the trailing ends of the vanes, an increase in rotative movement of the annular discharge or doughnut flow results and produces increased jet action which may be advantageously employed in VTOL and air cushion vehicle performance requirements.

A straight trailing edge on the vanes provides maximum volumetric capacity with median rotative movement of the discharge flow, while a backward curvature produces minimum rotative movement of the discharge flow with minimum sound level.

Between each pair of adjacent vanes, a twisted passage is defined, which at the intake end is elongated radially in cross section and at the discharge end is elongated circumferentially in cross section. The cross-sectional area of this passage is less at the discharge end than at the intake end with a substantial reduction taking place at the throat of the flare at the intake end of the fluid pump. The amount of twist of the passage between adjacent vanes will correspond in general to the pitch of the screw section.

Fluid pumps designed according to the invention may be conveniently installed in straight lengths of duct work, a common labyrinth seal being used between the duct work and opposite ends of the outer housing.

Detailed description In the illustrated form of the invention,

FIG. 1 is an end view of a fluid accelerator or pump taken from the discharge end,

FIG. 2 is a View similar to FIG. 1 taken from the intake end of the pump,

FIG. 3 is a side elevational view of the pump shown in FIGS. 1 and 2, with a single vane shown in dotted outline, and

FIG. 4 is a perspective view of one of the vanes removed from the assembly.

Referring to the drawings, the fluid pump 10, in its preferred form, comprises a conical-like member 12 and a dome-like member 14 carried on a shaft 16 in any suitable manner and adapted to rotate therewith as a unit. The shaft 16 may be the extension of the driven shaft on an electric motor or any other form of prime mover. The member 12 constitutes a rotating shroud and it is preferably supported from the member 14 by a plurality of vanes 18 attached along their longitudinal edges to the interior surface of the member 12 and the exterior surface of the member 14.

At the intake end 20 of the member 12 the peripheral edge portion is flared at 22 to provide a slightly restricted throat at 24. From the throat 24 to the discharge end 26 the member 12 is generally conical. The member 14 is substantially disposed within the member 12 and is carried in any suitable manner on the shaft 16- with the radially opposed interior and exterior surfaces of the members 12 and 14 defining an annular or doughnut discharge. Depending upon the material to be handled by the fluid pump, the cross-sectional area of the collective passages between the ends 20 and 26 may remain substantially constant or diminish.

The vanes 18 are shown as eight in number and are disposed 45 apart about the longitudinal axis of the shaft 16. Between the intake end 20 and the discharge end 26 the intermediate portion of the vanes have the surface thereof substantially defined by radial lines normal to the longitudinal axis of the shaft 16. Between the ends 20 and 26 the pitch of the main body portion of the vanes 18 with respect to the longitudinal axis of the shaft 16 can be in the order of to 45, depending upon the material to be handled by the fluid pump and the peripheral speed of the outer housing. The leading and trailing ends 28 and 30 of each vane 18 are preferably of a different configuration than the portion between the ends, as will be more fully described.

It will be appreciated that the width of each vane 18 between its terminal ends will be of varying shape and dimension in order to bridge the complex space between the members 12 and 14 between the ends and 26. In the area where the inner dome-like member 14 is not radially disposed from the outer housing member 12, the inner longitudinal edges of the vanes 18 are preferably substantially contiguous with the other surface of the shaft 16.

The cross-sectional area of the intake end 20 of the fluid pump substantially equals that of a circle having a diameter equal to that of the end 20 less the area of the shaft 16. At the throat 24 this intake area will be slightly less. Downstream but directly adjacent the throat 24 the area of the intake passage will increase. However, the cross-sectional area downstream between the members 12 and 14 will start to reduce the radial plane a and continue to be reduced to the discharge 26 with an accompanying acceleration of the fluid being forced along the passages between the vanes of the fluid pump.

In FIG. 4 is shown one of the vanes 18 of the eight of the illustrated embodiment. Prior to being formed, the flat blank of sheet material from which the vane 18 is fabricated is shown in dotted outline. The full line showing is the vane 18 in perspective after forming.

In the assembly of FIGS. 1-3, each vane 18 is attached along the edge portion bc to the exterior surface of the dome-like member 14. Edge portion c-d is unsupported and disposed in opposed relation to the shaft 16. Edge portion d-e is attached to the interior of the housing 12 between the throat 24 and intake 20. Edge portion e-f is attached to the interior of the housing 12 between the throat 24 and the discharge 26.

To provide support for the fluid pump 10 on the shaft 16, the member 14 is shown with a radial flange 14. In FIG. 1 the member 14 and flange 14' is shown broken away along the line g to fully expose one of the vanes 18 except for the edge d-e back of the flare 22 and the slight overlap of the f-d edge by the adjacent vane 18. It will be noted that the lead or pitch of the exposed vane along c-b is approximately 45. The screw portion of the vane 18 is generally defined by the edge portions b-c and ef. Edge portions c-d and de generally define the scoop portion of the impeller section at the intake end 20 and define the area which may be slightly angularly disposed to the screw section. The area of each vane directly adjacent the edge portion f-b of the trailing end 30 may be of a form interrupting that of the screw surface, or it may be a true continuation thereof depending upon the desired shape of the fluid stream leaving the discharge end 26.

It will be noted from FIG. 2 that the passage between adjacent vanes 18 at the intake end of the fluid pump 10 is of elongated cross-sectional form in a radial direction and that each such passage is disposed between the shaft 16 and the throat 24. However, such passages are twisted along their downstream course and atthe discharge end 24 take the cross-sectional shape shown in FIG. 1, namely, that of narrow circumferential slots of reduced area disposed between the exterior surface of the member 14 and the interior surface of the member 12 and the edge portions fb of adjacent vanes 18'.

To accommodate suitable labyrinth seals, the housing 12 is shown with radially projecting flanges 12' and 12".

It will be appreciated that the fluid being pumped is always being acted upon by the same side of each vane 18 as it is propelled through the impeller screw and centrifugal sections of the pump.

Having thus described my invention, what I claim to be new is:

1. A fluid impeller of the mix flow type comprising a rotating housing means, said housing means including an outer member having an upstream portion converging in a downstream direction to a minimum cross section and a downstream portion increasing in cross section to a maximum cross section, said housing means including an inner generally conical member of increasing cross section in a downstream direction, said inner member having an upstream end axially spaced downstream of said minimum cross section of said outer member and radially inwardly thereof, vanes extending between said inner and outer members, said vanes having free upstream leading inner edges depending from the outer member and starting approximately on the plane of minimum cross section of said outer member and terminating at said inner member, each of said vanes having upstream axial pumping portions curved in the direction of rotation of the impeller and extending from said outer member to said inner member, and a downstream centrifugal rearwardly curved portion, the curvature of the vanes being such whereby the fluid being impeller by said vanes is impelled solely by leading surfaces of said impeller vanes to be discharged axially from said housing and vanes.

(References on following page) References Cited UNITED STATES PATENTS Lorenz 103-115 Meisser 230 1 34.1

Burdett et a1. 230-119 Benoit 230-1341 6 FOREIGN PATENTS 8/ 1948 Australia. 9/1950 Great Britain.

HENRY F. RADUAZO, Primary Examiner.

U.S. Cl. X.R. 103-115; 170-168 

